Scroll type compressor

ABSTRACT

A scroll type compressor comprises a housing, a fixed scroll member fixed to the housing, a movable scroll member accommodated in the housing, a compression region defined with the fixed scroll member, a discharge port discharging gas from the compression region to a high pressure region, a first seal separating a predetermined region from a low pressure region adjacent to the periphery of the movable scroll member, an oil sump in the housing communicating with the high pressure region, and a passage in the housing extending from said oil sump to said predetermined region and permitting lubricating oil to supply the first seal due to the pressure difference between said predetermined region and the high pressure region. The gas is compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a scroll type compressor, especially to a device for feeding lubricating oil to a seal which is disposed between a movable scroll member and a housing in order to prevent gas leakage.

[0002] In a prior art, Japanese Unexamined Patent Publication No. 5-1682 discloses an example of a scroll type compressor. In this scroll type compressor, refrigerant gas compressed and pressurized in a compression region is discharged from a back surface side of a movable scroll member relative to the compression region. The scroll type compressor is a vertical scroll type compressor, an axis of a drive shaft of which is vertically arranged. In other words, an electric motor or a driving source of the scroll type compressor is installed to the upper side relative to the compression structure. The movable scroll member and a fixed scroll member constitute the compression structure. Lubricating oil in an oil sump is fed to a high pressure chamber via a passage. The oil sump is defined in a motor chamber accommodating the electric motor. The high pressure chamber is always filled with the refrigerant gas including the lubricating oil. The lubricating oil is fed due to the gravity, so that the lubricating oil is constantly fed to a seal ring.

[0003] On the other hand, in a horizontal scroll type compressor, in which an axis of a drive shaft is horizontally arranged, an electric motor and the compression structure are laterally installed in a housing. Additionally, a region of relatively higher pressure or a high pressure region, to which the refrigerant gas is discharged is defined in a back surface side of a movable scroll base plate. In this scroll type compressor, the refrigerant gas is compressed in the compression region, and is discharged from a discharge port of the movable scroll base plate to the high pressure region. An intermediate pressure region is defined between the high pressure region and a low pressure region accommodating the movable scroll base plate.

[0004] Such a horizontal scroll type compressor cannot apply the gravity for feeding the lubricating oil. Conventionally, a seal is disposed between lubricating intermediate pressure region and the low pressure region. Therefore, lubrication depends on the lubricating oil contained in the refrigerant gas leaked through a gap around a seal disposed between the high pressure region and the intermediate pressure region.

[0005] However, feeding the lubricating oil to the seal as mentioned above is not sufficient. The lubricating oil fed to the seal covers the surface of the seal, so that sealing performance of the seal is reinforced. Accordingly, as the lubricating oil decreases, the sealing performance is deteriorated.

SUMMARY OF THE INVENTION

[0006] The present invention addresses the above problems. To overcome the above problems, a scroll type compressor according to the present invention is capable of increasing the sealing performance, by feeding the lubricating oil enough to the seal due to pressure difference between a high pressure region and a predetermined region in the compressor.

[0007] In accordance with the present invention, a scroll type compressor comprises a housings a fixed scroll member, a movable scroll member, a compression region, a discharge port, a high pressure region, a first seal, a predetermined region, a low pressure region, an oil sump and a passage. The fixed scroll member is fixed to the housing. The movable scroll member is accommodated in the housing and defines the compression region with the fixed scroll member. Gas is compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member. The discharge port discharges the gas from the compression region to the high pressure region. The first seal separates the predetermined region from the low pressure region adjacent to the periphery of the movable scroll member. The oil sump in the housing communicates with the high pressure region. The passage in the housing extends from said oil sump to said predetermined region and permits lubricating oil to supply the first seal due to the pressure difference between said predetermined region and the high pressure region.

[0008] According to the present invention, an oil sump and a predetermined pressure region are intercommunicated via the passage. Thereby, the lubricating oil can be fed to a first seal via the passage due to pressure difference between pressure applied to the oil sump and pressure in the pre-determined region. The lubricating oil fed to the first seal increases, as compared with that of the prior art. Moreover, enough lubricating oil fed to the seal helps the first seal to improve the sealing performance, and the amount of the gas leakage decreases, and efficiency of compression improves. Such structure for feeding the lubricating oil due to the pressure difference does not select the type of the compressor such as the vertical type and the horizontal type. As long as the first seal is disposed at a higher position relative to the oil sump, the present invention can be applied.

[0009] Furthermore, in the present invention, a second seal is arranged between the high pressure region and the predetermined region. Preferably, the predetermined region is defined between the high pressure region and the low pressure region, and pressure in the predetermined region is lower than or equal to pressure in the high pressure region and is higher than pressure in the low pressure region. That is, the predetermined region is an intermediate pressure region. Accordingly, the lubricating oil fed due to pressure difference between pressure applied to the lubricating oil in the motor housing and pressure in the intermediate pressure region is maintained.

[0010] Preferably, the passage for feeding the lubricating oil to the first seal is provided with a throttle for regulating a flow rate. With the throttle, the pressurized refrigerant gas in the motor housing does not blow by through the passage into the predetermined region, so that efficiency of compression and lubrication cannot be deteriorated

[0011] Preferably, the lubricating oil is directly fed to a groove for fitting the first seal. Accordingly, the amount of the lubricating oil fed to the first seal increases. Additionally, the first soul is pressed against the back side of the movable scroll base plate due to pressure applied to the back surface side of the first seal facing to the bottom of the groove by feeding the lubricating oil into the groove, so that the scaling performance of the first seal is improved.

BRIEF DESCRIPTION OF THE DRAWING

[0012] The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

[0013]FIG. 1 is a longitudinal cross-sectional view illustrating a scroll type compressor incorporating the present invention;

[0014]FIG. 2 is an enlarged cross-sectional view of the compressor of FIG. 1 in the region of the structure for feeding lubricating oil to a seal in accordance with the present invention; and

[0015]FIG. 3 is an enlarged cross-sectional view of a second embodiment of the invention, partially cut away, to illustrate the structure for feeding lubricating oil to a seal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] One embodiment of the present invention applied to a scroll type compressor will now he described with reference to FIGS. 1 and 2, illustrating a horizontal scroll type compressor, wherein an axis of a drive shaft is generally horizontal.

[0017] As shown in FIG. 1, a fixed scroll member 2 is coupled to a front end of center housing 4. A motor housing 6 is coupled to the rear end of the center housing 4. A drive shaft 8 arranged in a horizontal direction is rotatably supported by the center housing 4 and the motor housing 6 via radial bearings 10 and 12. A crank shaft 14 is integrally formed at the front end of the drive shaft 4 so as to be radially offset from the axis of the drive shaft 4.

[0018] A bushing 16 is mounted to the crank shaft 14 so as to rotate integrally with the crank shaft 14. A balance weight 18 is fitted to the rear end of the bushing 16, rotates therewith. A movable scroll member 20 is rotatably mounted to the front end of the bushing 16 via needle bearing 22 so as to face to the fixed scroll member 2. Additionally, the needle bearing 22 is accommodated in a cylindrical boss 24 a extending from a movable scroll base plate 24 of the movable scroll member 20.

[0019] A fixed scroll base plate 26, a fixed spiral wall 28 of the fixed scroll member 2, the movable scroll base plate 24 and a movable spiral wall 30 of the movable scroll member 20 cooperatively form compression chambers 32, because the spiral walls 28 and 30 contact at plural points. The compression chambers 32 are sealed spaces, and are falcate. The fixed scroll member 2 and the movable scroll member 20 constitute compression mechanism 21. The movable scroll member 20 orbits (orbital motion) in accordance with the rotation of the crank shaft 14. Then, the balance weight 18 cancels centrifugal force generated by orbital motion of the movable scroll member 20. Orbiting mechanism for transmitting the orbital motion to the movable scroll member 20 is constituted of the crank shaft 14 which integrally rotates with the drive shaft 8, the bushing 16, and the needle bearing 22 interposed between the crank shaft 14 and the boss 24 a of the movable scroll member 20.

[0020] A plurality of recesses 34 (e.g. four in this embodiment) for preventing rotation is formed on an identical circumference in the front end surface of the enter housing 4 in equiangular positions. Fixed pins 36 are fixed to the center housing 4, and movable pins 38 are fixed to the movable scroll base plate 24. The movable pins 38 are accommodated in the associated recesses 34 so as to contact the fixed pins 36, respectively. The recesses 34, the fixed pins 36 and the movable pins 38 prevent the movable scroll member 20 from rotating due to the rotation of the crank shaft 14. In other words, the recesses 34, the fixed pins 36 and the movable pins 38 constitute a mechanism for preventing self rotation of the movable scroll member 20.

[0021] A stator 44 is secured to the inner circumferential surface of the motor housing 6. A rotor 45 is secured to the drive shaft 8. The stator 44 and the rotor 45 constitute an electric motor 46. The rotor 45 and the drive shaft 8 integrally rotate by energizing the stator 44. In other words, the electric motor 46 is installed in a sealed motor chamber 48 which is defined by the motor housing 6 and the center housing 4.

[0022] The movable scroll member 20 orbits due to the rotation of the crank shaft 14, which is radially offset from the drive shaft 8. Then, a gas to he compressed, such as refrigerant gas, introduced front an inlet 42 is enclosed in a space between the fixed scroll base plate 26 and the movable scroll base plate 24 at the peripheral sides of both the fixed and movable scroll members 2, 20. Meanwhile, the movable scroll member 20 tends to rotate around the axis of the bushing 16 due to the rotation of the crank shaft 14. However, the mechanism for preventing self rotation prevents the movable scroll member 20 from rotating.

[0023] Therefore, as the crank shaft 14 rotates, the movable scroll member 20, which is relatively and rotatably mounted to the crank shaft 14 via the needle hearing 22, orbits around the axis of the drive shaft 8 without itself rotating.

[0024] As the movable scroll member 20 orbits, the refrigerant gas introduced from the inlet 42 is enclosed in the compression chamber 32, and then the volume of the compression chamber 32 is progressively reduced and is moved radially inwardly from the outer circumference, thus converges in the space between the fixed spiral wall 28 and the movable spiral wall 30.

[0025] A discharge port 50 is formed through the center of the movable scroll base plate 24, and is communicated with the innermost compression chamber 32. A valve chamber 52 (a cylindrical groove) is formed at the back surface of the movable scroll base plate 24 (at the surface facing to the crank shaft 14), in the vicinity of the rear side of the discharge port 50. The discharge valve mechanism 54 is constituted of a reed valve 56 and a retainer 58.

[0026] A high pressure region 60 is defined in the vicinity of the center or the back surface of the movable scroll base plate 24. Pressurized refrigerant gas is discharged from the innermost compression chamber 32 to the high pressure region through the discharge port 50. The cylindrical boss 24 a extending from the back surface of the movable scroll base plate 24 surrounds the high pressure region 60. The valve chamber 52, which accommodates the discharge valve mechanism 54, also constitutes the high pressure region 60.

[0027] The high pressure region 60 is communicated with a motor chamber 48 via a discharge passage 62 formed along the axis of the drive shaft 8. The refrigerant gas in the motor chamber 48 is discharged to an external refrigerant circuit (not shown) via an outlet 64 formed through the rear wall of the motor housing 6. Outflow ports 62 a of the discharge passage 62 open to the circumferential surface of the drive shaft 14. As the refrigerant gas is discharged from the outflow ports 62 a, any lubricating oil included in the refrigerant gas is separated from the refrigerant gas by centrifugal force generated by the rotation of the drive shaft 14, and gravitates to an oil sump 48 a defined at the bottom of the motor chamber 48. The oil sump 48 a is defined at a lower position relative to the compression mechanism 21.

[0028] A region 66, corresponding to a predetermined region in the present invention, defined between the outer circumferential surface of the boss 24 a and the center housing 4, is separated relative to the high pressure chamber 60 by a seal 68, a seal ring 70 and an O-ring 72. The seal 68 is disposed its a groove in the surface of the bushing 16, with the seal ring 70 located between the boss 24 a and the bushing 16. The O-ring 72 is disposed between the crank shaft 14 and the bushing 16. Additionally, the region 66 is separated relative to a low pressure region 74 by a seal 76, and pressure in the inlet side is applied to the low pressure region 74. The low pressure region 74 accommodates the periphery of the movable scroll base plate 24 and is formed in the center housing 4. The seal 76 is disposed between the mating end surfaces of the movable scroll base plate 24 and the center housing 4.

[0029] Therefore, the region 66 constitutes an intermediate pressure region between the high pressure region 60 and the low pressure region 74. Pressure in the intermediate pressure region 66 is lower than or equal to pressure in the high pressure region 60, and is higher than pressure in the low pressure region 74. The intermediate pressure region 66 inhibits gas in the high pressure region 60 from leaking into the low pressure region 74. Also, pressure applied to the back surface of the movable scroll base plate 24 in the intermediate pressure region 66 restrains a deformation of the movable scroll base plate 24 so as to cancel force pressing against the front surface of the movable scroll base plate 24.

[0030] A seal 84 as a third seal is disposed between the drive shaft 8 and a shaft hole through the center housing 4. The third seal 84 separates the motor chamber 48 and the intermediate pressure region 66.

[0031] The seal 76 is disposed between the low pressure region 74 and the intermediate pressure region 66 so as not to communicate with each other, and occupies an annular groove 78, the cross section of which is rectangular (shown in FIG. 2). The seal 76 is disposed at a higher position relative to the oil sump 48 a in the motor chamber 48. In order to feed the lubricating oil stored in the oil sump 48 a to the first seal 76, a straight passage 80 formed in the housing 4 inclines upwardly to the passage opening 82 a from the oil sump 48 a. The passage 80 intercommunicates the oil sump 48 a and a region adjacent to the first seal 76 in the intermediate pressure region 66. Additionally, a throttle 82 for regulating a flow rate is located at the end of the passage adjacent to the intermediate pressure region 66.

[0032] In operation, the refrigerant gas is introduced from an external refrigerant circuit (not shown) into the compressor through the inlet 42, and is enclosed in the compression chamber 32. The refrigerant gas compressed and pressurized in the compression chamber 32 is discharged into the high pressure region 60 through the discharge valve 54, and passes through the discharge passage 62, and then into the motor chamber 48 via the outflow ports 62 a of the discharge passage 62. Meanwhile, the lubricating oil contained in the refrigerant gas is separated from the refrigerant gas by the centrifugal force. Thereafter, the lubricating oil is stored in the oil sump 48 a.

[0033] The lubricating oil in the oil sump 48 a flows into the intermediate pressure region 66 through the passage 80 due to pressure difference between the oil sump 48 a and the intermediate pressure region 66, and is fed to the first seal 76 via a gap between the center housing 4 and the movable scroll base plate 24 as best seen in FIG. 2. In this manner, the lubricating oil from the oil sump 48 a can be fed to the first seal 76, which is disposed at a higher position relative to the oil sump 48 a.

[0034] The refrigerant gas in the intermediate pressure region 66 tends to leak into the low pressure region 74 through a small gap between the surfaces of the first seal 76 and the movable scroll base plate 24 facing to each other. According to the present invention, the small gap between the first seal 76 and the movable scroll base plate 24 is supplied with the lubricating oil fed to the seal, and the refrigerant gas in the intermediate pressure region 66 leaking to the low pressure region 74 is retarded. Therefore, the sealing performance improves. Efficiency of air-conditioning of the compressor also improves due to a decrease in leakage of the refrigerant gas to the low pressure region 74. Additionally, abrasion-resistance of the first seal 76 improves.

[0035] During the operation of the compressor, the pressure difference between the intermediate pressure region 66 and the pressure applied to the oil sump 48 a may not be constant. Nevertheless, the pressure in the intermediate pressure region 66 does not exceed pressure applied to the oil sump 48 a. Owing to the seal 68, the seal ring 70 and the O-ring 72, and the supply of lubricating oil to the first seal 76 can be maintained.

[0036] The passage throttle 82 regulates the amount of flow of the refrigerant gas in the oil sump 48 a into the intermediate pressure region 66 through the passage 80. Therefore, deterioration of the efficiency of compression and insufficient lubrication due to the refrigerant gas, which includes the lubricant oil, blowing by through the passage 80 can be restrained. Locating the throttle 82 at the opening of the passage 80 adjacent to the intermediate pressure region 66, allows a large diameter in the rest of the passage 80, which helps to prevent clogging with sludge and so forth.

[0037] A second embodiment of the present invention will now be described with reference to FIG. 3. In the present embodiment, one opening of the passage 80 opens at the bottom of the annular groove 78 for fitting the first seal 76, and the other opening of the passage 80 opens at the oil sump 48 a. The passage 80 is provided for feeding the lubricating oil in the oil sump 48 a to the first seal 76. Additionally, the throttle 82 is not applied to the second embodiment. The other components of the compressor are the same as those of the first embodiment. In other words, the oil sump 48 a communicates with the groove 78. According to the second embodiment, the lubricating oil can be directly fed to the first seal 76.

[0038] As constructed above, the amount of the lubricating oil fed to the first seal 76 can be increased. In addition, the first seal 76 is pressed against the rear surface of the movable scroll base plate 24 due to pressure applied to the groove 78 by feeding the lubricating oil, and is also pressed against the inner wall surface of the groove 78 in a radial direction due to pressure applied to the groove 78 by feeding the lubricating oil. Therefore, the sealing performance improves.

[0039] The movable scroll base plate 24 may move in an axial direction due to variations of pressure difference between pressure in the compression chamber 32 and pressure applied to the back surface of the movable scroll base plate 24. The present invention, which can directly feed the lubricating oil to the groove 78, is effective in such structure. The first seal 76 also moves due to displacement of the movable scroll base plate 24 in the axial direction. Additionally, the first seal 76 is continuously pressed against the rear end surface of the movable scroll base plate 24. Therefore, the scaling performance of the first seal 76 can be maintained.

[0040] The present invention is not limited to the embodiments described above, but may be modified into examples as follows.

[0041] In the above embodiments, the electric motor 46 is applied to the scroll type compressor as a driving source. However, other driving source can be applied to the compressor in the present invention, such as engines, instead of the electric motor 46. Therefore, location of the oil sump 48 a is not limited to the bottom of the motor housing 48. The throttle 82 of the passage 80 can also be omitted. Additionally, the present invention can be applied to not only a horizontal scroll type compressor but also a vertical scroll type compressor, as long as a seal to feed the lubricating oil is disposed at a higher position relative to the oil sump.

[0042] According to the present invention, the first seal 76 for preventing gas leakage is disposed between the intermediate pressure region 66 and the 80 low pressure region 74, and feeding enough amount of the lubricating oil to the first seal 74 can be achieved. Thereby, the sealing performance of the first seal 76 improves.

[0043] The present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not limited to the details given herein but may be modified within the scope of the appended claims. 

What is claimed is:
 1. A scroll type compressor comprising: a housing; a fixed scroll member fixed to the housing; a movable scroll member accommodated in the housing and defining a compression region with the fixed scroll member, gas being compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member; a discharge port for discharging the gas from the compression region to a high pressure region; a first seal separating a predetermined region from a low pressure region adjacent to tho periphery of the movable scroll member; an oil sump in the housing communicating with the high pressure region; and a passage in the housing extending from said oil sump to said predetermined region, permitting lubricating oil to supply the first seal due to the pressure difference between said predetermined region and the high pressure region.
 2. A scroll type compressor according to claim 1 further comprising; a second seal disposed between the high pressure region and said predetermined pressure region, wherein pressure in said predetermined region is lower than or equal to the pressure in the high pressure region, and is higher than pressure in the low pressure region
 3. A scroll type compressor according to claim 1 further comprising: a throttle for regulating a flow rate of the gas arranged around an opening of said passage.
 4. A scroll type compressor according to claim 1, wherein said first seal is disposed in a recess formed in the housing; and wherein said passage is communicated with said recess.
 5. A scroll type compressor according to claim 1, wherein a driving source of the compressor is an electric motor. 